Rotorcraft Aeroelastic Stability Using Robust Analysis

This paper discusses the impact of different models of aerodynamic loads on rotorcraft-pilot couplings stability using a robust stability analysis approach. The aeroelasticity of the main rotor of a helicopter is formulated using aerodynamic models based on the blade element/momentum theory and boundary element method coupled to a finite element model of the blade. The resulting linearized models are used to determine stability limits according to the generalized Nyquist criterion, associated with the accelerations of the pilot’s seat caused by the involuntary action of the pilot on the control inceptors. The resulting stability curves are discussed considering examples of involuntary pilot transfer functions from the literature.